Transcript Mangrove Forests - Columbia University

Mangrove Forests
Dr. James A. Danoff-Burg
Columbia University
James A. Danoff-Burg, Columbia University, [email protected]
Mangrove Forests
• Found in coastal areas all over
the tropics
• Primarily in brackish water
– salty and fresh mix
• Cover approximately 22 million
hectares in tropical and
subtropical coasts
James A. Danoff-Burg, Columbia University, [email protected]
Ecosystem Functions &
Threats
• Serve as an important buffer
between sea and land
– Lessen impact of intense storms
– Reduce erosion and increase
sedimentation
– Important coastal pioneer species
– Act as basis for a complex, biologically
diverse, and productive ecosystem
• Increasingly threatened
– Human development is most intense
along coasts
James A. Danoff-Burg, Columbia University, [email protected]
Mangroves
• Not a natural taxonomic group
– Convergence among several groups
• Possibly 16 convergent events
– Based on physiological attributes
– 54 species total world-wide
• 16 Families
– Principally: Avicenniaceae & Rhizophoraceae
– These two families include 25 spp.
• 20 Genera
James A. Danoff-Burg, Columbia University, [email protected]
Mangrove Location
• Found in tropical areas only
– Within the 20ºC isocline
– More southern on East side of continents
• Due to southward moving warm Equatorial
currents there
James A. Danoff-Burg, Columbia University, [email protected]
Terminology
• Mangal
– Community of organisms in the
mangrove habitat
• Mangrove
– Trees that flourish in the mangal
• Pneumatophore
– Vertical root structures for air
exchange
– Lenticels - tiny pores for air exchange
– Aerenchyma – tissue for air storage
James A. Danoff-Burg, Columbia University, [email protected]
Characteristics of
Mangal
• Inundation with tides
• Increasing salinity towards ocean
• Sandy clay soil
– Nutrient poor
• Nitrogen & Phosphorus are limiting
– Limiting mangrove growth only
• Organic nutrients deposited via siltation
– Fresh water streams & down-shore currents
– Most all are of terrestrial origin
• In sum: Mangal is a harsh place to live
James A. Danoff-Burg, Columbia University, [email protected]
Mangrove Adaptations
• Salt tolerance
– Sequester in tissue (bark, stem, root)
– Secrete through leaves
– Exclusion by negative hydrostatic
pressure
• Frequent inundation
– Aerenchyma tissue & aerial roots
• Tolerant of soils low in oxygen
– Hypoxic or anoxic
James A. Danoff-Burg, Columbia University, [email protected]
Mangrove Consequences
of Adaptations
• Greater root mass
– Relative to rest of plant & relative to nonmangrove species
– For water exchange & air exchange
• Lower growth rates
– Consequence of salt & air exchange
• Tradeoff between salt tolerance &
frequent inundation
– Can adapt for one or other
– Not both
James A. Danoff-Burg, Columbia University, [email protected]
Mangrove Pollination
• Pollination method varies by
species
Wind (Rhizophora)
bat or hawk moth (Sonneratia)
birds and butterflies (Bruguiera)
bees (Acanthus, Aegiceras, Avicennia,
Excoecaria, Xylocarpus)
– fruit flies (Nypa)
– other small insects (Ceriops, Kandelia)
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James A. Danoff-Burg, Columbia University, [email protected]
Mangrove Reproduction
• Vivipary normal
– Reproduction and growth while still
attached to plant
• Flowering
• Fertilization
• Propagule growth
Young propagule a.k.a. Hypocotyl
Mature
propagule
James A. Danoff-Burg, Columbia University, [email protected]
Mangrove Dispersal
• Maturity -> Drop off maternal plant
• Float horizontally initially
– Dispersal to novel environments ideally
• Float vertically with appropriate
environmental conditions
• Rooting and growth
James A. Danoff-Burg, Columbia University, [email protected]
Mangal Habitat Types
(from inland to oceanfront)
• Riverine
– Often found in river deltas
– Constant influx of freshwater
– Great changes in salinity levels
• Basin Mangroves
– Inland, behind coastal mangroves
– Little change in tides, no wave action
– Often higher salinity than others (evaporation)
• Tide-Dominated
– Coastal front habitats
– Frequent sedimentation
– Unstable morphology due to coastal erosion
James A. Danoff-Burg, Columbia University, [email protected]
Intraspecific Differences in
Environmental Tolerances
• Salinity variations and adaptations for
excreting salt
– Varies within and between species
– Through growth stages
• Tidal Inundation and adaptations for gas
exchange
– Pneumatophores and other aerial root
extensions
• Low soil stability, Shore morphology, and
adaptations for rooting
– Prop Roots
• Sedimentation rates and types
James A. Danoff-Burg, Columbia University, [email protected]
Mangrove Species
Zonation
Bruguiera
gymnorrhiza
Ceriops
australis
Rhizophora
stylosa
Avicennia
marina
All increase toward shore
Salinity
Inundation
Decreasing Soil Stability
Sedimentation Rate
James A. Danoff-Burg, Columbia University, [email protected]
Most Common Species
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Red Mangrove
(Rhizophora mangle)
Black Mangrove
(Avicennia germinans)
White Mangrove
(Laguncularia racemosa)
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All are found throughout tropics
James A. Danoff-Burg, Columbia University, [email protected]
Bark Identification
James A. Danoff-Burg, Columbia University, [email protected]
Tree Characters
James A. Danoff-Burg, Columbia University, [email protected]
Pneumatophores
James A. Danoff-Burg, Columbia University, [email protected]
Epiphytes
James A. Danoff-Burg, Columbia University, [email protected]
For more information
• Go to
http://www.earthisland.org/map/mn
gec.htm and read the ecology link
• A clearinghouse on information on
mangrove ecology is available at
http://www.ncl.ac.uk/tcmweb/tcm/m
glinks.htm
James A. Danoff-Burg, Columbia University, [email protected]
Mangroves of Australia
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The mangrove plants of Queensland (from http://www.aims.gov.au/pages/reflib/fg-mangroves/pages/fgm-qld-15.html)
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Listed below are the true mangrove species that grow in Queensland. Hybrid plants are indicated by the use of an x in the scientific
name (e.g. Lumnitzera x rosea).
AcanthaceaeAcanthus ebracteatus Acanthus ilicifolius
ArecaceaeNypa fruticans
AvicenniaceaeAvicennia marina
BignoniaceaeDolichandrone spathacea
BombaceaeCamptostemum schultzii
CaesalpiniaceaeCynometra iripa
CombretaceaeLumnitzera racemosa, Lumnitzera x rosea, Lumnitzera littorea
EbenaceaeDiospyros ferrea
EuphorbiaceaeExcoecaria agallocha
LythraceaePemphis acidula
MeliaceaeXylocarpus granatum
MyrsinaceaeXylocarpus mekongensis, Aegiceras corniculatum
MyrtaceaeOsbornia octodonta
PlumbaginaceaeAegialitis annulata
PteridaceaeAcrostichum speciosum
RhizophoraceaeBruguiera gymnorrhiza,Bruguiera sexangula, Bruguiera exaristata, Bruguiera parviflora, Bruguiera
cylindrica, Ceriops australis, Ceriops decandra, Ceriops tagal, Rhizophora apiculata, Rhizophora x lamarckii,
Rhizophora stylosa, Rhizophora mucronata
RubiaceaeScyphiphora hydrophyllacea
SonneratiaceaeSonneratia alba, Sonneratia x gulngai, Sonneratia caseolaris, Sonneratia lanceolata
SterculaceaeHeritiera littoralis
James A. Danoff-Burg, Columbia University, [email protected]